Dong Qian, Song Xiaolei, Liu Haijun
Department of Mechanical Engineering, Temple University, Philadelphia, PA 19122, USA.
Sensors (Basel). 2020 Mar 22;20(6):1759. doi: 10.3390/s20061759.
An air-backed diaphragm is the key structure of most dynamic pressure sensors and plays a critical role in determining the sensor performance. Our previous analytical model investigated the influence of air cavity length on the sensitivity and bandwidth. The model found that as the cavity length decreases, the static sensitivity monotonically decreases, and the fundamental natural frequency shows a three-stage trend: increasing in the long-cavity-length range, reaching a plateau value in the medium-cavity-length range, and decreasing in the short-cavity-length range, which cannot be captured by the widely used lumped model. In this study, we conducted the first experimental measurements to validate these findings. Pressure sensors with a circular polyimide diaphragm and a backing air cavity with an adjustable length were designed, fabricated, and characterized, from which the static sensitivities and fundamental natural frequencies were obtained as a function of the cavity length. A further parametric study was conducted by changing the in-plane tension in the diaphragm. A finite element model was developed in COMSOL to investigate the effects of thermoviscous damping and provide validation for the experimental study. Along with the analytical model, this study provides a new understanding and important design guidelines for dynamic pressure sensors with air-backed diaphragms.
空气背衬膜片是大多数动态压力传感器的关键结构，在决定传感器性能方面起着至关重要的作用。我们之前的分析模型研究了空气腔长度对灵敏度和带宽的影响。该模型发现，随着腔长度的减小，静态灵敏度单调下降，基频呈现出三阶段趋势：在长腔长度范围内增加，在中腔长度范围内达到平稳值，在短腔长度范围内下降，而这一趋势无法被广泛使用的集总模型所捕捉。在本研究中，我们进行了首次实验测量以验证这些发现。设计、制造并表征了具有圆形聚酰亚胺膜片和长度可调的背衬空气腔的压力传感器，从中获得了作为腔长度函数的静态灵敏度和基频。通过改变膜片中的面内张力进行了进一步的参数研究。在COMSOL中开发了有限元模型，以研究热粘性阻尼的影响并为实验研究提供验证。连同分析模型一起，本研究为具有空气背衬膜片的动态压力传感器提供了新的理解和重要的设计指导。
